Sodium Nitrate
How to make sodium nitrate from calcium nitrate and sodium carbonate.
Calcium nitrate is commonly available in three forms: Use 350ml water total per mole reaction.
Name | Formula | NPK | Molecular Weight (g/mol) | Molar Nitrate Equivalent (g/mol) |
Calcium Ammonium Nitrate | 15.5-0-0 19% Ca | 1080.71 | 98.25 | |
Calcium Nitrate Tetrahydrate | 11.9-0-0 16.9% Ca | 236.15 | 118.08 | |
Calcium Nitrate Anhydrous | 17-0-0 23.6% Ca | 164.08 | 82.04 |
In the table below, the molar nitrate equivalent is the amount of the substance(s) required to produce 1 mol of Nitrate.
Alkali Table
Potassium is preferred as it is non hydroscopic while Sodium is preferred for alternative Aqua Regis mixtures because it lacks the Potassium.
Match up the Alkali quantities with the equivalent calcium nitrate, scale to the size you want, and mix. Then filter and dry the filtrate.
If you use potassium bicarbonate or sodium bicarbonate as your Alkali source you should first bake them in an oven at 200 Celsius for a couple of hours. This dries and converts the bicarbonates into their respective carbonates. This is important because the bicarbonates have lower solubility in water.
Example:
3 moles with Potassium Hydroxide.
3 * 350ml = 1050ml Water
Process
Begin with 500ml of water and 3 * 53g (159g) of Sodium Carbonate. If you are refining metals add about 20% more alkali to remove the calcium (180g). And recrystallize at the end for absolute purity.
In a separate container get another 500ml of water and using calcium ammonium nitrate (15.5-0-0) we require 3 mols: 3 * 98.25 (300g) to the water.
Once everything is dissolved the two solutions are added together and stirred vigorously for 3 minutes.
The Sodium Carbonate reacts with the calcium and ammonium nitrates to produce calcium hydroxide, calcium nitrates and a little ammonia gas. Do this in a fume hood. Most of the ammonia stays in the solution until evaporation.
IN a large pail with a colander lined with household cleaning paper (Bounty), with 3 layers minimum, filter the material into the bucket. Once most the fluid has pass through, fold the paper to enclose the material caught in the filter and squeeze as much fluid out as possible. The material remaining in this filter is Calcium Carbonate which can be used to neutralize acids.
The solution is Sodium Nitrate.
You can evaporate or boil this down to get sodium nitrate crystals (90%). This is very impure, containing left over contaminants from the nitrates and alkali. This is ok for use in the lab and for the manufacture of Nitric Acid or for the use as poor mans Nitric when combined with Sulphuric Acid.
If you want high purity, boil it down to 50%. Then filter while hot to remove the additional calcium hydroxide and let it cool. As it cools, much purer nitrate will precipitate out. Refilter and collect the nitrate crystals. The fluid can then be cooled in ice water which lowers the solubility of the nitrate or, reboil to another 50% and repeat.
Total yield is about 240g or 80%.
Step by Step:
Wear latex gloves and appropriate clothing.
Use a respirator as ammonium gas will be produced and is an irritant.
- Mix 180g of Sodium Carbonate in 500ml of distilled water.
- Mix 300g of Calcium Ammonium Nitrate (15.5-0-0) in 500ml of distilled water.
- Combine these in a large (3L) beaker and stir vigorously for 3 minutes.
- Let sit for approx. 40 minutes to an hour
- Filter the fluid in a colander placed over a bucket lined with 4 sheets deep of Bounty paper. Use clips to hold the paper and colander in place and pour the liquid into the filter, leaving solids until last.
- Once the fluid has passed through, remove the clips and fold the filter paper over the material caught in the filter. Replace the clips so the colander is secure to the bucket.
- Squeeze the folded paper to extract as much fluid as possible. The paper contains Calcium Carbonate which can be kept for lab use.
- Re-filter the liquid using a lab filter. This can be repeated again if necessary.
- Transfer the fluid to a large beaker (3L). There should be around 1L of fluid.
- Boil the fluid until there is enough to decant into a smaller beaker. e.g., 600 or 500 ml. And keep boiling,
- As the fluid boils down to around (XXX) it will begin to crystalize. It is important to continually observe and stir the contents to prevent the material from sticking to the beaker. Do not boil down to complete dry so that you can transfer the material to a Pyrex dish or equivalent to complete the dehydration. At this point you will need to constantly stir the material to prevent sticking but this less of a problem in a large dish versus the potential to break a beaker when you need to chisel out the material.
- Once the material is completely dry, use a coffee grinder to grind the material into a fine powder.
- Weigh and measure the yield.
Costs
A teaspoon is approximately 9g with a cost of $0.58 per teaspoon.
